from datetime import datetime

from tortoise import Model, fields
from tortoise.validators import MinValueValidator


class TimestampMixin:
    created_at: fields.Field[datetime] = fields.DatetimeField(
        auto_now_add=True,
    )
    modified_at: fields.Field[datetime] = fields.DatetimeField(
        auto_now=True,
    )


class Teilchen(TimestampMixin, Model):
    name: fields.Field[str] = fields.TextField(
        null=False,
    )
    description: fields.Field[str] = fields.TextField(
        null=False,
    )
    number: fields.Field[int] = fields.IntField(
        null=False,
        validators=[
            MinValueValidator(0),
        ],
    )

    tags: fields.ManyToManyRelation["Tag"] = fields.ManyToManyField(
        "models.Tag",
        through="models.TeilchenTag",
        related_name="teilchen",
        forward_key="tag_id",
        backward_key="teilchen_id",
    )


class Tag(TimestampMixin, Model):
    name: fields.Field[str] = fields.CharField(
        null=False,
        max_length=20,
    )


class TeilchenTag(Model):
    teilchen: fields.ForeignKeyRelation[Teilchen] = fields.ForeignKeyField(
        "models.Teilchen",
    )
    tag: fields.ForeignKeyRelation[Tag] = fields.ForeignKeyField(
        "models.Tag",
    )